1. Field of the Invention
The present invention relates to an imaging apparatus capturing an image using a solid-state imaging device and a method of processing an image in the imaging apparatus. More particularly, the present invention relates to an imaging apparatus and a method of processing an image which reduce the amount of data of an output image and, at the same time, improve the image quality.
2. Description of the Related Art
For a monitoring camera system which constantly monitors images captured by a camera and analyzing the images in order to detect the occurrence of abnormality, larger scale systems have become possible to be built at low cost with increases in camera performance and IP (Internet Protocol) transmission support on captured images. In such a monitoring camera system, it becomes possible to monitor multiple points at the same time by a plurality of cameras provided in the system. However, this brings about an increase in the amount of image information to be recorded. Also, the image information flowing in a system through a network increases. Thus, it has become a major task to reduce the volume of recording and the volume of transmitting images without deteriorating the image quality.
For the volume of transmission of an image captured by an imaging apparatus, it is desirable to control the volume so as to transmit the image at a maximum volume not exceeding a certain upper limit in accordance with the band of the network of the monitoring camera system. Thus, there has been devised a monitoring apparatus in which a camera is internally provided with a function of detecting abnormality in a monitoring target area, and the volume of transmission of image information is controlled by increasing or decreasing the image compression level in a codec section in accordance with the detection of an abnormal state (for example, refer to Japanese Unexamined Patent Application Publication No. 2000-50235 (paragraph numbers [0039] to [0043], FIG. 1)).
FIG. 9 is a functional block diagram illustrating a known IP monitoring camera. The incident light on an optical block 10 provided with a camera lens, etc., is converted into an electrical signal by an imaging device 11, such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor) sensor, etc., and becomes digital image data through a signal processing circuit 20. In this regard, the optical block 10 is connected to the signal processing circuit 20, and thus the movement of the camera lens, etc., is controlled.
The image data from the signal processing circuit 20 is individually sent to an image compression circuit 30 for compressing the amount of data, and to an intelligence circuit 40 for detecting an abnormal state and a noticed area of a moving object, etc. The image compression circuit 30 delivers the compression-coded image data to a network. When detecting an abnormal state from the input image data, the intelligence circuit 40 outputs the result to the outside as an alarm signal. In this case, if the image compression circuit 30 uniformly compresses the entire image, the image quality deteriorates seriously in the case of a narrow network band.
Thus, a captured image is divided into a plurality of screens by the signal processing circuit 20, and movement is detected for each of the divided images by the intelligence circuit 40. The image compression circuit 30 increases the compression rate on the divided images in which a movement has not been detected. Thus, it becomes possible to reduce the amount of data of the video data delivered from the image compression circuit 30, and to decrease the compression rate of the divided images in which movements have been detected to obtain high-quality image data. Accordingly, it becomes possible to maintain high image quality for important image parts while reducing the total amount of data, and to transmit the data on a network.